Dental tool.



F. H. SKINNER.

/ DENTAL TOOL.

APPLIOATION FILED JULY 1, 1907.

989,882. Patented Apr. 18, 1911.

FRANK HAMILTON SKINNER, OF CHICAGO, ILLINOIS.

DENTAL TOOL.

Specification of Letters Patent.

Patented Apr. 18, 1911.

T 0 all whom it may concern:

Be it known that I, FRANK H. SKINNER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Dental Tools, of whichthe following is a specification.

This invention relates to dental tools and has particular reference tocrown pin eX- tractors for removing dowel pins from the roots of teeth.

The object of my invention is to provide certain improvements in toolsof this class for the purpose of reducing their heretofore excessivecost and at the same time increasing their efficiency and advantages aswill hereinafter be described.

With the above-named objects in view my invention consists in theseveral novel features of construction hereinafter described,illustrated in the drawing and particularly pointed out in the claims.

In the drawingFigure 1 is a side elevation of a tool embodying myinvention showing the jaws open and the beaks gripping the dowel pin ina tooth. Fig. 2 is a similar view showing the jaws closed. Fig. 3 isalongitudinal section taken on line XX of Fig. 4:. Fig. 4 is a sectiontaken on line Y-Y of Fig. 3. Fig. 5 is a perspective view of the centralpost shown in Figs. 1 to a.

Fig. 6 is an enlarged view of the beaks of the forceps or vise-jawsbroken away, together with a tooth and dowel pin being gripped by saidbeaks.

In the several views 2 and 3 represent a pair of vise-jaws joined by anintegral spring portion 4. In the latter is an opening 5 for a screw 6which has threaded engagement with the driving post 7. The latterconsists of an interiorly threaded cylindrical portion 8, a loop 9providing a slot 10, and prongs 11 and 12. The slot 10 is engaged by ascrew 13 passing through a bore 14: in the jaw 2 and having threadedengagement with a threaded opening 15 in the jaw 3. A shoulder or flange16 on the screw supports the screw against lengthwise movement in thejaw 2 under stress of gripping of the jaws. A pair of collars 17 and 18secured to or shrunk on the screw 6 holds the latter againstlongitudinal movement relatively to the spring portion 4 of the jaws,while the post 7 is free to move between the jaws when the screw 6 isturned in the threaded portion 8. At the beaks 19 and 20 of the jaws 2and 3 depressions 21 and 22 are formed to enable the beaks to enter avery narrow space about a dowel pin 23 in the root of a tooth 24. Across-piece or bridge 25 arranged between the loop 9 and the tips of theprongs and very closely to the beaks, supports the prongs firmly againstspringing apart when forcibly brought to bear against a tooth.

The general reciprocal operation of the beaks and prongs is the same asin other devices heretofore constructed for this purpose, but in myinvention are found the following advantages 2 The curved spring base 4,4:, for the jaws 2 and 3, not only sets the latter apart, but affordssuilicient elastic movement to prevent breakage at their junction. Whenthese jaws are moved toward each other they take a firm grip on a brokendowel pin with slight projection beyond the tooth. The above-describedconstruction further affords an arrangement and combination whichresults in a compact construction, convenient manipulation, greateraccessibility than heretofore into the limited space that dental toolsmust operate in, and the tool as a whole is less terrifying orformidable in appearance to a patient than long handled forceps and thelike. The compactness of construction is attained largely by not onlymaking the jaws in a single piece (which has been done heretofore), but

by also mounting the screw against longitudinal movement relatively tothe jaws and by letting the screw which advances the post enter saidpost and have a long or powerful threaded engagement therewithin. Thisgives a minimum of exposure to the post advancing screw, which exposureis substantially only the thumb piece thereof. The single piece 7 iscentrally arranged with respect to the beaks and with respect to theforce applied upon and atatooth. Said piece is also a container of theadvancing screw; it is also a guide cooperating with the screw 13 tosupport the post laterally (thereby saving special provisions for thatpurpose,) and in said single piece is also contained the prongs 11 and12 and the bridge or support 25 for the prongs. In the double prongarrangements heretofore provided the general construction of the toolhas not permitted the placing of a prong support near the tips of theprongs, in con sequence of which the prongs have sprung apart under thestrain of operation and often caused injury to and suffering of thepatient. Additional advantages of the compact constructions are: Thepower is applied closely to the point of resistancethe beaks or theplace where the work is done; the patient is spared the undue jarringsincidental to large and clumsy tools, and space is saved in the dentiststool-tray. The last'mentioned advantage is by no means insignificantwhen it is remembered that a dentists tool-tray must be equipped with aliberal variety of instruments. In pulling a pin from the root of atooth with the aid of my improved device, the forces are dis tributedequally on both sides of the axis of the screw 6, which prevents theside strains incidental to single-prong tools, and which strains tend totilt the tool and cause itto slip and injure the patient.

Having thus described my invention, I claim as new and desire to secureby Letters Patent 1. In combination with the jaws, of a spring-basecommon to both jaws, means for moving said jaws toward each other, apost having a part adapted to rest upon the root of a tooth, and meansfor moving said post.

2. In combination with the jaws, of the spring-base therefor, the screwfor moving the jaws toward each other, the pronged central postconstructed and arranged to be guided by said screw and means for movingsaid post.

3. The combination with the jaws, of the wide and resilient spring-basefor said jaws, the post having a pair of prongs, and the screws foractuating said jaws and post, re spectively, said screws cooperating tosupport the post longitudinally and laterally.

4. In combination with the jaws having a spring-base common to both andmeans for moving said jaws relatively to each other, of the post havinga part adapted to bear against the root of a tooth, and the screw havingthreaded engagement with said post and mounted against longitudinalmovement relative to said jaws.

5. In combination with the jaws having the recessed beaks and theoperating screw 13, of the wide spring-base therefor, the screw 6 heldagainst longitudinal movement in said base, the post having thecylindrical and interiorly threaded portion which engages said screw 6,said post having the loop 9 which engages said screw 13 and is supportedlaterally thereby, said post having also the prongs 11 andl2 and thebridge 25 arranged between said loop and the tips of the prongs wherebythe latter are firmly supported as set forth.

6. The combination, with the jaws, ofa post having prongs arranged tocooperate with said jaws, means for supporting said prongs at the beaksof the jaws as set forth, and means for moving said post.

7. The combination with the jaws joined by the spring-base 4:, of thescrew journaled in said base, a post having threaded engagement withsaid screw, said post provided with prongs arranged at the sides of saidjaws, saidprongs having a bridge or crossbar 25 arranged near theextremities or beaks of the jaws, whereby said prongs are firmlysupported against springing apart under the strain of operation.

8. In a dental tool for removing crown pins, the combination with a visehaving spring jaws with tapered ends adapted to engage the pin and screwthreaded means disposed transversely of said jaws and adapted to drawthem tightly together upon the pin, of a thrust-member slidably mountedin said vise and at one endlying alongside of the pin-engaging ends ofsaid jaws, and means engaging the other end of said thrust-member toeffect a relative longitudinal movement between the latter and the vise,substantially as described.

In testimony whereof I have hereunto signed my name in the presence oftwo subscribing witnesses.

FRANK HAMILTON SKINNER.

Witnesses J W. BECKSTROM, M. C. ALLEN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

